| 摘要 |
PROBLEM TO BE SOLVED: To provide a tungsten sealed glass excellent in ultraviolet solarization, ultraviolet screening properties, devitrification resistance and electrical insulating properties and suitable as a glass tube for a fluorescent lamp of a back light or a front light. SOLUTION: The glass has the composition (by mass%) of 65 to 76 SiO2, 0 to 25 B2O3, 2 to 6 Al2O3, 0.5 to 5.8 MgO+CaO+SrO+BaO+ZnO, 3 to 8 Li2O+ Na2O+K2O, 0.01 to 4 Fe2O3+CeO2 0 to 10 TiO2+Sb2O3+PbO and 0 to 2 ZrO2 and satisfies Na2O/(Na2O+K2O)<=0.6.
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